Edit system, edit control device, and edit control method

ABSTRACT

A splicer/transcoder  21  interfaces with a material archiver/server using a stream. The splicer/transcoder  21  interfaces with an editor and switcher  22  using a base band signal. In a predetermined region including at least an edit point, a transcoding process is performed. In an input stream, two programs to be edited have been multiplexed. The editor and switcher  22  receives base band signals Sa and Sb of which respective programs have been encoded. As with a conventional editing device, the editor and switcher  22  edits the base band signals and returns the edited result as a base band signal Sc to the splicer/transcoder  21 . The splicer/transcoder  21  re-encodes the base band signal Sc into an output stream using codec information obtained in the decoding process.

TECHNICAL FIELD

The present invention relates to an editing system, an editingcontrolling apparatus, and an editing controlling method that handle abit stream.

BACKGROUND ART

With compressing technologies such as MPEG (Moving Picture ExpertsGroup) system that have been recently used for digital broadcasts, manyprograms can be broadcast through a limited transmission medium (awireless transmission medium or a wired transmission medium). Likewise,when a broadcast provider transmits programs, the rental fee of atransponder of a satellite circuit is expensive. Thus, from a view pointof cost, it is effective to compress an occupied band-width. Thissituation is the same with a material transmission using a ground waveor a commercial wire circuit. Thus, when data is transmitted from a siteto a broadcasting station or data is transmitted between broadcastingstations, it is meaningful to use an MPEG stream.

A major benefit for applying a compressing technology such as MPEGsystem to a picture material in a broadcasting station is to reduce thestorage capacity of a picture material archiver/server. When anon-linear editing operation was not required, a picture material wasarchived on a tape whose running cost is low. However, since thenon-linear editing operation has been required in recent years, it isnecessary to reduce the storage capacity of a non-linear record medium(hard disk, DVD, or the like).

Next, with reference to FIG. 15, an outline of a transmission systemcorresponding to MPEG standard will be described. The transmissionsystem has an encoder portion 110 and a decoder portion 120. The encoderportion 110 has a video data portion and an audio data portion. Thevideo data portion comprises a video encoder 111 and a packetizer 112.The video encoder 111 encodes input video data D_(V) and outputs a videoelementary stream ES. The packetizer 112 packetizes the video elementarystream ES received from the video encoder 111, adds a header and soforth thereto, and outputs a video packetized elementary stream PES. Theaudio data portion of the encoder portion 110 comprises an audio encoder113 and a packetizer 114. The audio encoder 113 encodes input audio dataD_(A) and outputs an audio elementary stream ES. The packetizer 114packetizes the audio elementary stream ES received from the audioencoder 113, adds a header and so forth thereto, and outputs a videopacketized elementary stream PES. The encoder portion 110 also has amultiplexer 115. The multiplexer 115 multiplexes the elementary streamsreceived from the packetizers 112 and 114, generates transport streampackets (each of which is composed of 188 bytes), and outputs them as atransport stream TS.

The decoder portion 120 of the transmission system shown in FIG. 15comprises a demultiplexer 121, depacketizers 122 and 124, a videodecoder 123, and an audio decoder 125. The demultiplexer 121demultiplexes the transport stream received through a transmissionmedium 116 into a video PES and an audio PES. The depacketizers 122 and124 depacketize the video PES and the audio PES, respectively. The videodecoder 123 decodes the video ES received from the depacketizer 122. Theaudio decoder 125 decodes the audio ES received from the depacketizer124. The video decoder 123 outputs a base band video signal D_(V). Theaudio decoder 125 outputs a base band audio signal D_(A). The decoderportion 120 is referred to as IRD (Integrated Receiver/Decoder).

Concentrating on video data, the operation of the system shown in FIG.15 will be described. In the encoder portion 110, the video encoder 111encodes an input video data D_(V) of which each picture has the same bitquantity, converts each picture to a bit quantity corresponding to itsredundancy, and outputs the resultant data as a video elementary stream.The packetizer 112 absorbs (averages) the fluctuation of the bitquantity of the video elementary stream on the time base and outputs theresultant data as a video packetized elementary stream. The transportstream multiplexer 115 multiplexes the video packetized elementarystream received from the packetizer 112 and the audio packetizedelementary stream received from the packetizer 114, generates themultiplexed data as transport stream packets, and supplies them as atransport stream TS to the decoder portion 120 through the transmissionmedium 116.

In the decoder portion 120, the transport stream demultiplexer 121demultiplexes a transport stream into a video packetized elementarystream and an audio packetized elementary stream. The depacketizer 122depacketizes the video packetized elementary stream and outputs theresultant data as a video elementary stream. The video decoder 123decodes the video elementary stream and outputs the resultant data asvideo data D_(V).

The decoder portion 120 performs a variable bit quantity extractingprocess for each reproduced picture from a received stream with a fixedbit rate using for example a 1.75 Mbit VBV (Video Buffering Verifier)buffer. Thus, the encoder portion 110 should control a generated bitquantity of each picture so as to prevent the VBV buffer fromoverflowing or underflowing. Such a controlling process is referred toas VBV buffer process.

As described above, from view points of effective use of limitedtransmission resources for a multi-channel broadcasting system and areduction of the running-cost of a transmission circuit, it is veryattractive to use an encoded stream. However, an MPEG streamcorresponding to a highly efficient compressing system has restrictionsagainst broadcast materials.

The compressing technology of the MPEG system has the followingfeatures: (1) In the MPEG system, an encoding process is performedcorresponding to frame correlation of each GOP (Group Of Picture). (2)Each picture that has been encoded corresponding to the MPEG format hasa variable bit length. (3) In MPEG2 format, the bit rate is controlled(a process of the VBV buffer) so that the buffer condition of thedestination IRD is satisfied. (4) When an encoding process correspondingto the MPEG2 format is performed for transmitting data, the bit rate ofthe data is controlled corresponding to the capacity of a transmissionpath.

Due to the features of the MPEG system, when an MPEG bit stream isreceived and edited, the following problems will take place. In otherwords, when data is edited for each frame, after an MPEG stream isdecoded to a base band signal, the data should be edited. Thereafter,the resultant base band signal should be encoded into an MPEG stream.Thus, whenever an editing operation including a switching operation isperformed, the encoding process and the decoding process are repeated.Normally, when a decoding-encoding chain of a base band signal to anMPEG stream is performed, the resultant picture largely deteriorates.When an encoded bit stream is switched at any position, even if it is atthe end of an encoding unit (in reality, even in a closed GOP structurethat does not use the correlation of GOPs), the continuity of the buffercontrolling operation is lost. Thus, the restrictions of the VBV buffercannot be satisfied. As a result, a decoded picture freezes or breaksbecause the buffer overflows or underflow.

Due to such problems, it was said that it is substantially impossible toedit data as an MPEG stream. Thus, even if a compressed multi-channelbroadcast corresponding to MPEG system is performed, a means for editinga base band material and finally encoding the edited data into an MPEGstream is used. When an original material is an MPEG stream, after thebase band signal is decoded into a base band signal, it is edited by aconventional base band editing device. Thus, after the editing operationis performed, the resultant picture quality remarkably deteriorates. Inaddition, when a special effect such as gain adjustment is performed orwhen a logo of a broadcasting station is inserted, the MPEG streamcannot be used.

Next, such problems will be practically described with several examplesof an editing system in a broadcasting station. FIG. 16 shows masterservers and an interface of an editing studio. Each of the masterservers has an MPEG stream archiver. In the broadcasting station, datais sent as a base band signal. In FIG. 16, reference numeral 101 is amaster archiver/server in a broadcasting station. The archiver/server101 is a non-linear archiver that has a storing portion. The storingportion stores a material of an MPEG compressed stream so as to reducethe data amount of the material. Both the archiver and the server storepicture materials. However, the archiver is a device that dedicatedlystores a picture material. In contrast, the server outputs a picturematerial corresponding to a request received from an external device.According to the present invention, since both the archiver and theserver have a function as a picture storing portion, the presentinvention can be applied to both the archiver and the server. Thus, inthe specification, a term archiver/server is used.

The archiver/server 101 has an MPEG decoder that decodes an MPEG streamreceived from the storing portion. Base band video data S1 and S2generated by an MPEG decoder are input to the editing studio 102. Atransmission protocol of transmission paths in the broadcasting stationis based on a base band signal. The editing studio 102 performs anediting operation for connecting the video data S1 and S2 (spliceediting operation, AB roll operation, or the like). Video data S3 (abase band signal) that has been edited is input to the archiver/server103. The archiver/server 103 has an MPEG encoder. The MPEG encodersupplies the edited result as an MPEG stream to a storing portion.

FIG. 17 shows an example of the structure of the editing studio 102.Since the data amount of video data of a base band signal is large(namely, the bit rate thereof is high), a tape medium is used as arecord medium. In other words, video data S1 is recorded to a linearstorage 104 a. Video data S2 is recorded to a linear storage 104 b. Thelinear storages 104 a and 104 b function as players. The video data Saand Sb are supplied to an editor and switcher 105. Video data Sc as anedited result of the editor and switcher 105 is recorded to a linearstorage 104 c that functions as a recorder. The linear storage 104 coutputs edited data as video data S3.

As shown in FIG. 18, the editing studio 102 may be composed ofnon-linear storages 106 a, 106 b, and 106 c that use non-linear recordmediums (hard disks, optical discs, and so forth). However, when a baseband signal is handled with a non-linear record medium, since the dataamount of the base band signal is large, the record medium is expensive.Thus, the structure of which a linear storage is disposed to eachediting studio is not practical. In the editing system shown in FIG. 16,whenever an editing operation is performed, a decoding-encoding chaintakes place. Thus, the picture quality of a material cumulativelydeteriorates.

FIG. 19 shows master servers and an interface of an editing studio inthe case that a transmission protocol of transmission paths in abroadcasting station is an MPEG stream. An archiver/server 131 and anarchiver/server 133 store materials as MPEG streams. The archiver/server131 outputs an MPEG stream to an editing studio 132. The archiver/server131 receives an MPEG stream from the editing studio 132. Thus, thearchiver/server 131 and the archiver/server 133 do not have an MPEGdecoder and an MPEG encoder. With an MPEG stream, two or more picturematerials can be multiplexed as streams TS1 and TS2. In such amulti-channel system, transmission paths can be effectively used. Thestreams TS1 and TS2 may be elementary streams or transport streams.

FIGS. 20 and 21 show a first example and a second example of the editingstudio 132 of the system shown in FIG. 19, respectively. In the firstexample shown in FIG. 20, a stream TS1 is decoded into streams TS1 a andTS1 b. MPEG decoders 134 a and 134 b convert the streams TS1 a and TS1 binto respective base band signals. The resultant base band signals arestored to linear storages 135 a and 135 b. Base band video data Sa andSb obtained by the linear storages 135 a and 135 b that function asplayers are supplied to a base band editor and switcher 136. The baseband editor and switcher 136 supplies the edited result as video data Scto a linear storage 135 c that functions as a recorder. Video datareceived from the linear storage 135 c is supplied to an MPEG encoder134 c. The MPEG encoder 134 c outputs encoded data as an MPEG streamTS2.

In the second example of the editing studio 132 shown in FIG. 21,non-linear storages 137 a, 137 b, and 137 c are used instead of thelinear storages 135 a, 135 b, and 135 c, respectively. In the exampleshown in FIG. 21, an MPEG stream can be sent through a transmission pathof a broadcasting station so that a multi-channel system can be easilystructured. However, in the first and second examples shown in FIGS. 20and 21, whenever an editing operation is performed, a decoding-encodingchain takes place. Thus, the picture quality of the material unignorablydeteriorates. In addition, the picture quality cumulativelydeteriorates. Moreover, when a base band signal is handled with anon-linear record medium, since the data amount of the base band signalis large and the non-linear record medium is expensive, the secondexample shown in FIG. 21 of which a non-linear record medium is disposedin each broadcasting station is not practical.

To prevent a material from deteriorating against a decoding-encodingchain, a material is archived as a base band material. In this case,since the data amount of a picture material becomes large, it isdifficult to store it to a non-linear record medium.

As a means for solving problems of material deterioration and recordcapacity, it is preferred to edit data as a stream. However, to do that,there are problems due to the features of the MPEG stream. To solvethese problems, there are several methods. For a problem of overflow,the number of bits of each picture is counted. The VBV buffer issimulated so as to insert dummy data thereto. However, for a problem ofunderflow, no solving method is known. In this case, a picture freezes.

On the other hand, a bit rate controlling method is known. In thismethod, before an encoding process is performed, a switching point isdesignated so that a predetermined buffer amount takes place at theswitching point. In this method, the problem of VBV buffer will besolved. However, the problem is solved at only the predeterminedswitching point. Thus, the scope of this method is limited.

In addition, to solve a problem of deterioration of picture quality dueto a decoding-encoding chain, when a stream is decoded, informationnecessary for an encoding process and a decoding process is extractedand multiplexed with a base band signal. The information is referred toas codec information. When a re-encoding process is performed, with thecodec information, the accuracy of reconstruction of a picture isimproved. This process is referred to as trans codec process. The codesinformation contains information of moving vector, quantizing step,picture type, and so forth.

The information amount of codec information is not small. Thus, sincethe base band signal does not have a sufficient auxiliary region inwhich the codec information is multiplexed, the remaining codecinformation should be multiplexed with a valid picture region ortransmitted through another line.

FIG. 22 shows an example of the structure of which an editing studio isstructured with a transcoding process. The transcoding process isperformed so as to prevent the picture quality of a material fromcumulatively deteriorating against a decoding-encoding chaincorresponding to each editing operation. In FIG. 22, codec informationis sent through a path different from a material signal line. MPEGdecoders 134 a and 134 b convert streams TS1 a and TS1 b into respectivebase band signals as base band video data Sa and Sb. The base band videodata Sa and Sb are supplied to a base band editor and switcher 136. Thebase band editor and switcher 136 supplies the edited result as videodata Sc to an MPEG encoder 134 c. The MPEG encoder 134 c re-encodes thevideo data Sc and outputs the re-encoded data as an MPEG stream TS2.

The editing studio shown in FIG. 22 also has information detectors 141 aand 141 b, signal lines 142 a, 142 b, and 142 c, an informationestimator 144, and a codec information adaptor 143. The informationdetectors 141 a and 141 b detect codec information used in the MPEGdecoders 134 a and 134 b from streams or the decoders 134 a and 134 b,respectively. The signal lines 142 a, 142 b, and 142 c transmit codecinformation. The information estimator 144 allows the encoder 134 c touse the codec information. The codec information adaptor 143 organicallyconnects the codec information with the edit information of the baseband editor and switcher 136.

When codec information is sent through another line, the editor andswitcher 136 performs an editing operation. To handle codec informationsent through another system, a special structure such as the codecinformation adaptor 143 should be added. In other words, a conventionalediting studio that handles a base band signal cannot be used.

FIG. 23 shows the structure of an editing studio that allows such aproblem to be solved. In other words, in the structure shown in FIG. 23,codec information is multiplexed with a valid region of a base bandsignal. The editing studio shown in FIG. 23 has information detectors141 a and 141 b that detect codec information from input streams TS1 aand TS1 b or decoders 134 a and 134 b, respectively. Imposers 145 a and145 b multiplex the detected codec information with video data Sa and Sbas the base band signals, respectively. The multiplexed base bandsignals are supplied to a base band editor and switcher 136. As anexample of the multiplexing method, codec information is randomlymultiplexed as the least significant bit of each sample of video data.

The base band editor and switcher 136 outputs video data in which codecinformation has been multiplexed. The video data is supplied to aseparator 146. The separator 146 separates codec information from thevideo data received from the base band editor and switcher 136. Thevideo data Sc separated by the separator 146 is supplied to an MPEGencoder 134 c. The MPEG encoder 134 c re-encodes the video data Sc usingthe codec information received from the separator 146.

FIG. 24 shows the structure of which non-linear storages 147 and 148 areadded to the structure shown in FIG. 23. The non-linear storage 147outputs a stream that has been recorded and reproduced to MPEG decoders134 a and 134 b. The non-linear storage 148 records a stream that isre-encoded by an MPEG encoder 134 c.

As shown in FIGS. 23 and 24, when codec information is multiplexed witha base band signal and then the multiplexed signal is transmitted, thebase band editor and switcher 136 does not need a special device such asa codec information adaptor. However, in the method of which codecinformation is inserted into a valid region of a picture signal, even ifthe codec information is converted into random data and then multiplexedwith a picture signal, a picture distorts and the S/N ratio thereofdeteriorates.

In the structures shown in FIGS. 23 and 24, when codec information ismultiplexed with a base band signal, a multiplexing means is disposed inan editing studio. FIG. 25 shows an example of the structure of which ameans for multiplexing and demultiplexing codec information is disposedin an archiver/server. Referring to FIG. 25, a archiver/server 151comprises MPEG decoders 155 a and 156 a, information detectors 155 b and156 b, and imposers 157 a and 157 b. The MPEG decoders 155 a and 156 adecode an MPEG stream received from a storing portion 154. Theinformation detectors 155 b and 156 b detect codec information fromrespective streams. The imposers 157 a and 157 b multiplex codecinformation with video data as base band signals.

Video data S11 and S12 in which codec information has been multiplexedare supplied to an editing studio 152. The editing studio 152 handles abase band signal. As with the structure shown in FIG. 24, the editingstudio 152 is composed of a linear storage and a base band editor andswitcher.

Video data S13 as a base band signal in which codec information receivedfrom the editing studio 152 has been multiplexed is supplied to anarchiver/server 153 that stores video data as an edited result. Aseparator 158 separates codec information from the video data S13. AnMPEG encoder 159 re-encodes the resultant video data using the codecinformation. A stream received from the MPEG encoder 159 is stored to astoring portion 160. However, actually, the structure shown in FIG. 25does not correctly function. In other words, connections in thestructure shown in FIG. 25 are invalid. In the editing studio 152, videodata is recorded to a conventional record medium such as a VTR (VideoTape Recorder) that records a base band signal. Of course, theconventional VTR does not support a function for extracting codecinformation and supplying the extracted codec information to the nextstage. Moreover, since most conventional digital VTRs use a compressingsystem other than the MPEG system, information multiplexed in a validregion of a signal is compressed and decompressed in the same manner asvideo data. Thus, since codec information is compressed anddecompressed, the resultant video data distorts. Consequently, the codecinformation cannot be used. Even if codec information is superimposed atthe least significant bit of video data, the least significant bit isvaried by the compressing process and the decompressing process of theVTR.

On the other hand, in the structures shown in FIGS. 23 and 24, a streamis transmitted. Additional structural elements such as an MPEG decoderand a re-encoder are disposed in an editing studio. Thus, a probabilityfor interfacing a conventional VTR with a base band signal in whichcodec information has been multiplexed is excluded. However, asdescribed above, when codec information is inserted into a valid regionof a picture signal, the resultant picture distorts and the S/N rationthereof deteriorates.

Therefore, an object of the present invention is to provide an editingsystem, an editing controlling apparatus, and an editing controllingmethod that allow a storage medium and a transmission medium to beeffectively used, the picture quality to be suppressed fromdeteriorating, and a conventional base band editing device to be used.

Another object of the present invention is to provide an editing system,an editing controlling apparatus, and an editing controlling method thatallow an edit position to be detected without need to obtaining editposition information from an editing device.

A further object of the present invention is to provide an editingsystem, an editing controlling apparatus, and an editing controllingmethod that allow codec information for a re-encoding process to be usedin a unit smaller than a picture and the picture quality of a re-encodedpicture to be prevented from deteriorating.

DISCLOSURE OF THE INVENTION

Claim 1 of the present invention is directed to an editing system havingan editing device for editing a base band signal and an editingcontrolling device connected to the editing device. The editingcontrolling device comprises a first decoding means for decoding a firstencoded bit stream of which a material has been encoded and outputting afirst base band signal, and a second decoding means for decoding asecond encoded bit stream of which a material has been encoded andoutputting a second base band signal to the editing device. An encodingmeans is also provided for re-encoding a third base band signal as anedited result of the first base band signal and the second base bandsignal received from the editing device with codec information used inthe first decoding means and the second decoding means and outputting athird encoded bit stream. A controlling means for selecting codecinformation used by the first encoding means and the second encodingmeans corresponding to edit position information received from anexternal device is also provided.

Claim 8 of the present invention is directed to an editing controllingapparatus. The apparatus comprises a first decoding means for decoding afirst encoded bit stream of which a material has been encoded andoutputting a first base band signal, and a second decoding means fordecoding a second encoded bit stream of which a material has beenencoded and outputting a second base band signal to an editing device.The apparatus also includes an encoding means for re-encoding a thirdbase band signal as an edited result of the first base band signal andthe second base band signal received from the editing device with codecinformation used in the first decoding means and the second decodingmeans and outputting a third encoded bit stream. A controlling means isalso provided for selecting codec information used by the first encodingmeans and the second encoding means corresponding to edit positioninformation received from an external device.

Claim 15 of the present invention is directed to an editing controllingmethod. The method comprises the steps of inputting a first encoded bitstream of which a first material has been encoded and a second encodedbit stream of which a second material has been encoded, and sending toan editing device a first base band signal and a second base band signalof which the first encoded bit stream and the second encoded bit streamhave been decoded respectively. The method further comprises the stepsof receiving a third base band signal as an edited result of the firstbase band signal and the second base band signal from the editingdevice, selecting required codec information of codec information usedfor decoding the first encoded bit stream and the second encoded bitstream corresponding to edit position information received from anexternal device, and re-encoding the third base band signal with theselected coded information and outputting a third encoded bit stream.

Claim 16 of the present invention is directed to an editing controllingapparatus having an editing device for editing a base band signal and anediting controlling device connected to the editing device. The editingcontrolling device comprises a first decoding means for decoding a firstencoded bit stream of which a material has been encoded and outputting afirst base band signal, and a second decoding means for decoding asecond encoded bit stream of which a material has been encoded andoutputting a second base band signal to the editing device. The editingcontrolling device further comprises a comparing means for comparing thefirst base band signal, the second base band signal, and the third baseband signal in the state that the phases thereof match so as to detectan edit position, a controlling means for selecting codec informationused in a re-encoding process corresponding to information of the editposition, and an encoding means for re-encoding the third base signal asan edited result of the first base band signal and the second base bandsignal received from the editing device using the selected codecinformation and outputting a third encoded bit stream.

Claim 19 of the present invention is directed to an editing controllingapparatus. The editing apparatus comprises a first decoding means fordecoding a first encoded bit stream of which a material has been encodedand outputting a first base band signal, and a second decoding means fordecoding a second encoded bit stream of which a material has beenencoded and outputting a second base band signal to an editing device.The editing controlling apparatus further comprises a comparing meansfor comparing the first base band signal, the second base band signal,and the third base band signal in the state that the phases thereofmatch so as to detect an edit position, a controlling means forselecting codec information used in a re-encoding process correspondingto information of the edit position, and an encoding means forre-encoding the third base signal as an edited result of the first baseband signal and the second base band signal received from the editingdevice using the selected codec information and outputting a thirdencoded bit stream.

Claim 22 of the present invention is directed to an editing controllingmethod. The method comprises the steps of inputting a first encoded bitstream of which a first material has been encoded and a second encodedbit stream of which a second material has been encoded, and sending toan editing device a first base band signal and a second base band signalof which the first encoded bit stream and the second encoded bit streamhave been decoded respectively. The method further comprises the stepsof storing the first base band signal, the second base band signal, andcodec information used in the decoding process of the first base bandsignal and the second base band signal, receiving a third base bandsignal as an edited result of the first base band signal and the secondbase band signal from the editing device, and comparing the first baseband signal with the third base band signal in the state that the phasesof the first base band signal and the third base band signal match andcomparing the second base band signal with the third base band signal inthe state that the phases of the second base band band signal and thethird base band signal match so as to detect an edit position. Themethod finally comprises the steps of selecting codec information usedin the re-encoding process of the third base band signal correspondingto the detected edit position, and re-encoding the third base bandsignal with the selected coded information and outputting a thirdencoded bit stream.

According to the present invention, since the input/output signal formatof the editing controlling is an encoded bit stream, encoded data of aplurality of picture materials can be easily multiplexed. Thus, atransmission medium can be effectively used. In addition, the editingcontrolling apparatus interfaces with the editing device using a baseband signal. Moreover, codec information is not multiplexed with a baseband signal. In addition, it is not necessary to transmit codecinformation used for a transcoding process through another signal line.Thus, the number of signal lines can be prevented from increasing.Consequently, the conventional base band editing apparatus can bedirectly used as an editing device.

In addition, since a first base band signal and a second base bandsignal that are output to the editing device are compared with a thirdbase band signal received from the editing device in the state that thephases thereof match, an edit position can be detected. Thus, a line fortransmitting edit position information to the editing device can beomitted. Moreover, it is not necessary to interpret edit positioninformation into time base information of a stream.

In addition, the validity of the use of codec information for are-encoding process can be determined for each block as well as eachpicture. Thus, even if two original materials co-exists in a picture atan edit point, the deterioration of the picture quality against are-encoding process can be suppressed.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram showing the overall system structure of abroadcasting station according to a first embodiment of the presentinvention;

FIG. 2 is a block diagram showing an example of an editing studioaccording to the first embodiment of the present invention;

FIG. 3 is a block diagram showing another example of the editing studioaccording to the first embodiment of the present invention;

FIG. 4 is a block diagram showing an example of a broadcasting networkaccording to the present invention;

FIG. 5 is a block diagram showing an example of a splicer/transcoder asa principal portion according to the first embodiment of the presentinvention;

FIG. 6 is a block diagram showing an example of the structure of amanagement information generating portion of the splicer/transcoder;

FIG. 7 is a block diagram showing another example of the structure ofthe splicer/transcoder as a principal portion according to the firstembodiment of the present invention;

FIG. 8 is a block diagram showing another example of the structure ofthe splicer/transcoder as a principal portion according to a secondembodiment of the present invention;

FIG. 9 is a schematic diagram for explaining chronological relation baseband signals and a process for re-using codec information;

FIG. 10 is a schematic diagram showing the relation between pictures andmacro blocks;

FIG. 11 is a flow chart showing a determining process for the re-use ofcodec information;

FIG. 12 is a flow chart showing a picture sub-routine shown in FIG. 11;

FIG. 13 is a flow chart showing a macro block sub-routine shown in FIG.11;

FIG. 14 is a schematic diagram for explaining the re-use of codecinformation for each macro block;

FIG. 15 is a block diagram showing a conventional MPEG encoding/decodingsystem;

FIG. 16 is a block diagram showing an example of the structure of asystem in a broadcasting station as a reference for explaining thepresent invention;

FIG. 17 is a block diagram showing an example of the structure of anediting studio shown in FIG. 16;

FIG. 18 is a block diagram showing another example of the editing studioshown in FIG. 16;

FIG. 19 is a block diagram showing another example of the structure ofthe system in the broadcasting station as a reference for explaining thepresent invention;

FIG. 20 is a block diagram showing an example of an editing studio shownin FIG. 19;

FIG. 21 is a block diagram showing another example of the editing studioshown in FIG. 19;

FIG. 22 is a block diagram showing an example of the structure of anediting studio as a reference for explaining the present invention;

FIG. 23 is a block diagram showing another example of the structure ofthe editing studio as a reference for explaining the present invention;

FIG. 24 is a block diagram showing the structure of which a non-linearstorage is added to the structure shown in FIG. 23; and

FIG. 25 is a block diagram showing the structure of a system in abroadcasting station as a reference for explaining the presentinvention.

BEST MODES FOR CARRYING OUT THE INVENTION

Next, with reference to the accompanying drawings, an embodiment of thepresent invention will be described. FIG. 1 shows the structure of anediting system according to the present invention. An archiver/server 1and an archiver/server 3 have storing portions 4 and 5, respectively.The storing portions 4 and 5 store picture materials of encoded bitstreams for example MPEG streams. Since MPEG streams have beencompressed corresponding to MPEG format, non-linear record mediums canbe used as the storing portions 4 and 5. Both the archiver and theserver store picture materials. However, the archiver is a device thatdedicatedly stores a picture material. In contrast, the server outputs apicture material corresponding to a request received from an externaldevice. According to the present invention, since both the archiver andthe server have a function as a picture storing portion, the presentinvention can be applied to both the archiver and the server. Thus, inthe specification, a term archiver/server is used.

In transmission paths from the archiver/server 1 to the editing studio 2to the archiver/server 3, encoded bit streams (for example, MPEGstreams) are transmitted. Thus, since a plurality channels aremultiplexed, transmission resources can be effectively used. In otherwords, in a stream TS1 transmitted from the archiver/server 1, two ormore original video/audio materials are multiplexed. A stream TS2 is astream as an edited result. However, when necessary, an edited resultand two or more video/audio materials can be multiplexed. In thisexample, the streams TS1 and TS2 are transport streams. Alternatively,the streams TS1 and TS2 may be packetized elementary streams.

The editing studio 2 is structured as shown in FIG. 2 or FIG. 3. In anexample shown in FIG. 2, the editing studio 2 has a splicer/transcoder21 and a base band editor and switcher 22. The splicer/transcoder 21inputs a stream TS1 and outputs a stream TS2. The base band editor andswitcher 22 inputs video data Sa and Sb as base band signals and outputsvideo data Sc so as to interface with the splicer/transcoder 21 usingbase band signals. The splicer/transcoder 21 functions as an editingcontrolling apparatus. The base band editor and switcher 22 functions asan editing device.

The splicer/transcoder 21 is basically a transcoder that performs adecoding process for converting an input stream into a base band signalthat is output to the editor and switcher 22 and a re-encoding processfor converting a base band signal received from the editor and switcher22 into an output stream. As will be described later, the transcodingprocess may be performed in a predetermined region including an editpoint. An input stream or an output signal of the transcoding processmay be switched. In other words, the splicer/transcoder 21 may functionas a splicer. Thus, in the example, the term “splicer/transcoder” isused.

In another example of the editing studio shown in FIG. 3, non-linearstorages 23 a and 23 b are added to the structure shown in FIG. 2. Thenon-linear storage 23 a records a stream TS1 received from anarchiver/server 1 and supplies a stream TS11 to a splicer/transcoder 21.The non-linear storage 23 b records a stream TS12 received from thesplicer/transcoder 21 and outputs a stream TS2.

As are clear from FIGS. 2 and 3, the input/output signals of thesplicer/transcoder 21 are MPEG streams. Thus, since multiple channelsare easily multiplexed, transmission resources can be effectively used.In addition, the base band editor and switcher 22 can interface with thesplicer/transcoder 21 using base band signals.

In addition, since the splicer/transcoder 21 performs a transcodingprocess, it does not need to output codec information necessary for anre-encoding process to the editor and switcher 22. Thus, with aconventional base band signal editing device as the base band editor andswitcher 22, an editing system can be structured.

Moreover, the splicer/transcoder 21 correlates an MPEG picture(including codec information) of an input stream ST1 with a frame (or afield) of a base band input/output signal. When the editor and switch 22requires time code information is required, it is sent from thesplicer/transcoder 21 to the editor and switcher 22 through abidirectional signal line connected therebetween. The time codeinformation corresponds to the relation between an MPEG picture and atime code defined in the splicer/transcoder 21. In other words, timemanagement information of an MPEG picture used in the splicer/transcoder21 just corresponds to time management information (time code) used inthe editing operation of the editor and switcher 22.

The return time of the edited base band signal Sc from the base bandeditor and switcher 22 is obtained by adding the output time of the baseband signal Sc and the system delay of the base band editor and switcher22. Codec information necessary for a re-encoding process can be easilycorrelated with a frame of a return base band signal Sc by recording theoutput time of the base band signal of the splicer/transcoder 21.

In addition, the splicer/transcoder 21 receives edit positioninformation such as cue information as a conventional time code from thebase band editor and switcher 22 or a host CPU (or a control machine)that controls the base band editor and switcher 22 and correlates theedit position information with an MPEG picture. In other words, thesplicer/transcoder 21 detects an edit frame corresponding to cueinformation and selects codec information used in a re-encoding process.The codec information contains for example moving vector, picture type,quantizing step size, and quantizing scale.

To correlate a time code with an MPEG picture, a correlation table thatrepresents the relation between a PTS (Presentation Time Stamp) of anymaterial and a time code is inserted into for example an input stream.The correlation table may be transmitted in various manners. Forexample, the correlation table may be transmitted as a section typeindependent packet. Alternatively, the correlation table may be placedin a user area such as an extension of the stream syntax.

As another alternative method, a time code correlating with an MPEGpicture may be inserted into a stream and the resultant stream may betransmitted. In this case, the correlation table is not required. Thetransmission time information is not limited to a time code. During anediting operation, a picture index just corresponding to a time code maybe transmitted in a sufficient time designation range. Moreover, withinformation such as PTS, picture type, GOP, and repeat first fieldcorresponding to pull down operation and field flip operation as asyntax of an MPEG stream (rules of an encoded data stream), a time codecan be correlated with cue information.

FIG. 4 shows an outline of the structure of a broadcasting systemaccording to the present invention. Referring to FIG. 4, a centerstation 31 is connected to a plurality of local stations 32 a, 32 b, 32c, 32 d, . . . through a transmission network 33. An MPEG bit stream istransmitted through the transmission network. With an MPEG bit stream,many channels can be multiplexed and transmitted. The center station 31has an antenna 35 that receives a radio wave from acommunication/broadcasting satellite 34. A program material received bythe antenna 35, a live material received from a site through a microwavecircuit 36, and a program material and a CM material received from anarchiver/server 41 in the center station 31 are supplied as MPEG streamsto a splicer/transcoder 42.

As described above, the splicer/transcoder 42 has a base band interfacewith a base band editor and switcher 43. The splicer/transcoder 42selects input program materials and generates a broadcast program (as anMPEG bit stream). The center station 31 transmits the broadcast programto the local stations 32 a, 32 b, . . . through the network 33.

In the local station 32 a, an MPEG stream received from the centerstation 31 and a CM (Commercial Message) material received from a CMserver 46 a are input to a splicer/transcoder 44 a. Thesplicer/transcoder 44 a and a CM insertion scheduler 45 a are connectedwith a base band interface. The CM server 46 a stores CM materialscreated by the local station 32 a. The CM insertion scheduler 45 asubstitutes a CM contained in a program bit stream received from thecenter station 31 with a local CM of the local station 32 a. With thetranscoding process, a local CM can be substituted almost free ofdeterioration. Likewise, in other local stations 32 b, 32 c, . . . ,their local CMs can be substituted.

In addition to the substitution of a local CM, the center station 31 andthe local stations 32 a, 32 b, . . . can insert their logos into programbit streams. Moreover, along with ground wave broadcasts, the presentinvention can be applied to the relation between a cable operator andhead end stations of a CATV system.

FIGS. 5 and 7 show a first example and a second example of the structureof the splicer/transcoder 21. In the first example shown in. FIG. 5, aninput MPEG bit stream is fully transcoded. In the second example shownin FIG. 7, after an input MPEG bit stream is partly transcoded, theresultant stream is switched (spliced).

Next, the first example of the structure of the splicer/transcoder shownin FIG. 5 will be described. An MPEG bit stream TS1 such as an outputsignal of an archiver/server, a signal received from a satellite, or asignal received through a microwave circuit is input to thesplicer/transcoder. The stream TS1 is a stream of which a plurality ofprograms (program materials) have been multiplexed. In the stream TS1,at least two programs have been multiplexed. In this example, the streamTS1 is a transport stream TS. Alternatively, the stream TS1 may be atime-division multiplexed elementary stream ES. However, in the case ofthe elementary stream ES, an identification tag or input informationthat identifies the current input stream is required.

Reference numeral 51 is a filter that extracts packets of two programsto be edited. In the case of a transport stream TS, with a PID (packetID), a desired program can be extracted. In the case of an elementarystream ES, as described above, information such as an identification tagis required.

MPEG decoders 52 a and 52 b decode two streams A and B extracted by thefilter 51. The MPEG decoder 52 a obtains base band video/audio data Saof the program A. The MPEG decoder 52 b obtains base band video/audiodata Sb of the program B. The base band data Sa and Sb are output to anexternal editor and switcher 22.

The base band editor and switcher 22 outputs return base bandvideo/audio data Sc that has been edited to the splicer/transcoder. Thebase band data Sc is supplied to an MPEG re-encoder 53. The re-encoder53 receives codec information for an MPEG re-encoding processcorresponding to a video frame of the base band data Sc from aninformation buffer 55 through a path 54. Corresponding to the codecinformation for the re-encoding process, the data Sc is re-encoded for adesired bit quantity. The re-encoder 53 outputs a stream TS2 as theresult of an AB roll editing operation of the input streams A and B. Thecodec information for the re-encoding process contains for examplemoving vector, picture type, quantizing step size, and quantizing level.With the transcoding process, the deterioration of the picture qualitydue to a decoding-encoding chain can be suppressed.

The splicer/transcoder interfaces with the editor and switcher 22 usingonly the base band data Sa, Sb, and Sc. Thus, it is not necessary tosuperimpose codec information with base band data. In FIGS. 5 and 7, atransmission path for transmitting a time code to the splicer/transcoder21 corresponding to a request from the editor and switcher 22 isomitted.

Codec information used in the MPEG decoders 52 a and 52 b is input tothe information buffer 55. A write address WAD and a write enable WE aresupplied from a write controller 56 to the information buffer 55. Inaddition, a read address RAD is supplied from a read controller 57 tothe information buffer 55. The information buffer 55 should supply codecinformation for the re-encoding process to the re-encoder 53 insynchronization with an edit point of the stream Sc. When video data Scof which video data Sb has been connected to video data Sa at an editpoint (in point) is returned, the codec information for re-encoding thevideo data Sa is switched to the codec information for re-encoding thevideo data Sb. The storage capacity of the information buffer 55 maycorrespond to the system delay (a time period for several frames) of theeditor and switcher 22.

The phases of the video data Sa and the video data Sb received from thesplicer/transcoder 21 and the phase of the video data Sc returned fromthe base band editor and switcher 22 are managed by a management table62. Thus, the write controller 56 and the read controller 57 areconnected to the management table 62. The management table 62 controlsthe write/read operations of the information buffer 55 with the picturecount value of the input stream and the frame count value of the returnvideo data Sc. A frame counter 58 counts the number of frames of thevideo data Sc and sends a read request REQ with a read addresscorresponding to the count value to the management table 62. Themanagement table 62 has a structure of a ring buffer of which inputinformation is successively written to an incremented address and that aread pointer is incremented corresponding to the read request REQ.Re-encode information of an address represented by the read pointer isread from the information buffer 55 and sent to the MPEG re-encoder 53through the path 54. In association with the management table 62, amanagement information generating portion 61 is disposed. Cueinformation is input to the management information generating portion 61(that will be described later).

Cue information for editing a program is supplied from the editor andswitcher 22 or the control master to the management informationgenerating portion 61 of the splicer/transcoder. The cue information isnormally edit position information designated with a time code. Inreality, cue information contains information of in-point/out-point.Corresponding to cue information, an edit frame is detected. Codecinformation is selected so that it is used in synchronization with thebase band data Sc. When predetermined codec information is read by theread controller 57, an enable signal that represents that the codecinformation can be used is supplied from the read controller 57 to there-encoder 53.

The re-encoder 53 is connected to a bit quantity estimator 59. The bitquantity estimator 59 performs a VBV buffer process. In other words,with the bit quantity estimator 59, the re-encoder 53 properly performsa re-encoding process so that the buffer of the decoder that decodes theMPEG bit stream TS2 does not overflow or underflow. To do that, a targetbit quantity (information for assigning and weighting a generated bitquantity) in the vicinity of an edit point is supplied to the bitquantity estimator 53. The target bit quantity is written in a relevantindex slot of the management table 62. When the re-encoding process isperformed, the target generated bit quantity is satisfied. In the normalencoding process, when the generated bit quantity of the re-encoder 53is insufficient against the designated target bit quantity, dummy datais added. In contrast, when the generated bit quantity exceeds thetarget bit quantity (in other words, in the situation that the buffer ofthe decoder will underflow), a macro block skipping process or a processfor causing the predictive residual (namely, the difference between amacro block MB of a predictive picture and the relevant one of theconsidered picture) to be zero is performed. When such a process doesnot prevent the buffer from underflowing, the reproduced picture isaffected by the processing method on the decoder side. Normally, untildata is stored to the buffer, the reproduced picture freezes.

FIG. 6 shows a detailed structure of the management informationgenerating portion 61. Cue information as edit position information issupplied to a interpreter 71. When necessary, the interpreter 71interprets the cue information. The resultant information that is outputfrom the interpreter 71 is supplied to a mapping device 72. The mappingdevice 72 maps the cue information represented as a time code to a scaleof a time stamp PTS (time management information of a reproduced outputsignal) of an input stream 73 extracted by the filter 51.

A picture counter 74 detects picture headers from the input stream 73and counts the number of pictures. The number of pictures counted by thepicture counter 74 is supplied to a picture/frame index generator 75.The picture/frame index generator 75 generates an index for pictures soas to arrange pictures and information of the management table 62. Themanagement table 62 arranges the contents corresponding to the index andoutputs management information with an address as the count value offrames of the video data Sc received from the frame counter 58.

A time stamp reader 76 reads a time stamp PTS from the input stream 73.The time stamp PTS and an output signal of the mapping device 72 aresupplied to a re-encoding strategy planner 77. The output signal of themapping device 72 is the result of which a time code that represents anedit point of a video frame has been mapped to the scale of a timestamp. Thus, the re-encoding strategy planner 77 correlates an editpoint with a picture of the input stream 73. An output signal of there-encoding strategy planner 77 is written to a relevant address of themanagement table 62 corresponding to the index.

Reference numeral 78 is a picture bit quantity counter that counts thegenerated bit quantity of the input stream 73. The picture bit quantitycounter 78 supplies the counted result to a VBV buffer simulator 79. TheVBV buffer simulator 79 simulates a VBV buffer. The VBV buffer has thestorage capacity of the buffer on the decoder side. The storage capacityof the VBV buffer is estimated in the encoding process of the encoder.When the VBV buffer is simulated, the buffer on the decoder side can beprevented from underflowing or overflowing. The simulated result of theVBV buffer simulator 79 is supplied to the re-encoding strategy planner77. The re-encoding strategy planner 77 assigns and weights a generatedbit quantity in the vicinity of an edit point so as to perform are-encoding process. The assigned and weighted bit quantity is writtento a relevant index slot of the management table 62.

FIG. 7 shows the second example of the structure of thesplicer/transcoder 21. In this example, the transcoding process isperformed in the required minimum region that is affected by an editingoperation. The input stream is switched with the transcoded stream. Inthis example, the deterioration of the picture quality that cannot besolved with the transcoding process can be remarkably suppressed.

The difference between the second example shown in FIG. 7 and the firstexample shown in FIG. 5 is in that an input stream 73 received from afilter 51 is stored in a picture buffer 63 and that a stream receivedfrom a picture buffer 63 is switched to a stream received from are-encoder 53 by a switching circuit 66.

In the second example shown in FIG. 7, a write controller 64 and a readcontroller 65 are disposed. The write controller 64 controls the writeoperation of the picture buffer 63. The read controller 65 controls theread operation of the picture buffer 63. The write controller 64 and theread controller 65 are controlled with a management table 62. Thepicture buffer 63 is controlled so that the above-described codecinformation is written to the information buffer 55 and that codecinformation for a re-encoding process is read from the informationbuffer 55.

In the case of video data Sc of which video data Sa is switched to videodata Sb, before the transcoding process is performed in the vicinity ofan edit point, the switching circuit 66 selects a stream correspondingto the data Sa received from the picture buffer 63. After thetranscoding process is performed, the switching circuit 66 selects astream corresponding to the data Sb received from the picture buffer 63.The selecting operation of the switching circuit 66 is controlledcorresponding to a control signal 67 received from the read controller65. The storage capacity of the picture buffer 63 may be equivalent tothe system delay (a time period for several frames) of the editor andswitcher 22 plus the delay of the encoding process (several pictures).Thus, the picture buffer 63 does not adversely affect the structure ofthe system.

Next, a second embodiment of the present invention will be described.The outline of the structure of the editing system of to the secondembodiment is the same as that of the first embodiment (see FIGS. 1, 2,and 3). The second embodiment can be applied to a broadcasting system aswith the first embodiment (see FIG. 4). In the first embodiment of thepresent invention, a stream of an original material is encoded. Codecinformation of the encoding process is stored. Only a decoded base bandsignal is supplied to an editing device. The editing device edits a baseband signal, matches the phase of the base band signal as the editedresult with the stored codec information corresponding to cueinformation, re-encodes the base band signal as the edited result, andoutputs the re-encoded signal as a stream. According to the firstembodiment, since data is transmitted as a stream, the storage capacityof the record medium of the storing means can be reduced. In addition, atransmission medium can be effectively used. Moreover, with thetranscoding process, the deterioration of picture quality can beremarkably suppressed. Furthermore, a conventional base band editingdevice can be directly used as an editing device.

In the first embodiment, since the conventional editing device thathandles a base band signal represents an edit position with a time code,the edit position information should be interpreted so as to map theedit position information on a stream. In addition, the edit positioninformation contains edit positions for frames or fields (and durationwhen a switching function such as a wipe operation is used). Thus, theedit position information does not represent a switching transitionstate in a frame (or a picture in the stream). Thus, codec informationfor a re-encoding process cannot be finely used in a frame.

On the other hand, according to the second embodiment of the presentinvention, such problems can be solved. In other words, without editposition information, first and second base band signals that are outputto the editing device and a third base band signal that is returned fromthe editing device can be compared in the state that the phases of thesesignals match. Thus, a line for transmitting edit position informationto the editing device can be omitted. In addition, it is not necessaryto interpret the edit position information into the time axis of thestream.

Moreover, the validity of the use of codec information for a re-encodingprocess can be determined for each block as well as for each picture.Thus, even if two original materials co-exist in a picture at an editpoint, the deterioration of the picture quality against the re-encodingprocess can be suppressed.

Thus, in the second embodiment, the splicer/transcoder 21 shown in FIGS.1, 2, and 3 compares the output base band signals Sa, Sb, and the returnbase band signal Sc. Corresponding to the compared result, thesplicer/transcoder 21 detects an edit position and selects codecinformation for a re-encoding process. The edit position informationcontains an edit position for each frame (picture) and edit data foreach smaller block of each picture. The codec information contains forexample moving vector, picture type, quantizing step size, andquantizing scale. To detect an edit position, a picture buffer thatstores an original material is required. The storage capacity of each ofthe picture buffer and the information buffer is as small as thatequivalent to the system delay (around several frames) of the editor andswitcher 22.

FIG. 8 shows an example of the structure of the splicer/transcoder 21according to the second embodiment of the present invention. In theexample shown in FIG. 8, an input MPEG bit stream is fully transcoded.Alternatively, after an input MPEG bit stream is partly transcoded, astream may be switched (spliced). In other words, in a predeterminedregion including an edit point, a stream of which the base band signalSc has been transcoded is selected. In other than the predeterminedregion, an input stream is selected. These operations are performed by aswitching means. In the example of which an input stream is partlytranscoded, since a decoding-encoding chain is performed for a part ofthe stream, the deterioration of the picture quality is remarkablysuppressed.

Next, with reference to FIG. 8, the example of the structure of thesplicer/transcoder will be described. An MPEG bit stream TS1 that is forexample an output signal of an archiver/server, a signal received from asatellite, or a signal received through a microwave circuit is input.The stream TS1 is a stream of which a plurality of programs (programmaterials) have been multiplexed. In the stream TS1, at least twoprograms have been multiplexed. The stream TS1 may be an elementarystream ES of which signals have been time division multiplexed. In thecase of the elementary stream ES, an identification tag or inputinformation that identifies the current input stream is required.

Reference numeral 251 is a filter that extracts packets of two programs(original materials) A and B to be edited. In the case of the transportstream TS, the filter 251 extracts a desired program corresponding to aPID (packet ID). In the case of the elementary stream ES, as describedabove, information such as an identification tag is required. The filter251 outputs a stream 268 of which the selected two programs A and B havebeen multiplexed.

The two programs A and B extracted by the filter 251 are decoded by MPEGdecoders 252 a and 252 b, respectively. The MPEG decoder 252 a obtainsbase band video/audio data Sa of the program A. The MPEG decoder 252 bobtains base band video/audio data Sb of the program B. These base banddata Sa and Sb are output to the external editor and switcher 22. Inaddition, the base band data Sa and Sb are stored to a picture buffer263. A write controller 264 and a read controller 265 are disposed. Thewrite controller 264 controls the write operation of the picture buffer263. The read controller 265 controls the read operation of the picturebuffer 263. A write address WAD and a write enable WE are supplied fromthe write controller 264 to the picture buffer 263. Likewise, a readaddress RAD is supplied from the read controller 265 to the picturebuffer 263.

Codec information used in the decoding processes of the MPEG decoders252 a and 252 b is input to an information buffer 255. A write addressWAD and a write enable WE are supplied from the write controller 256 tothe information buffer 255. A read address RAD is supplied from the readcontroller 257 to the information buffer 255. The information buffer 255should supply codec information for the re-encoding process to there-encoder 253 in synchronization with an edit point of the stream Sc.When video data Sc of which video data Sb has been connected to videodata Sa at an edit point (in point) is returned, the codec informationfor re-encoding the video data Sa is switched to the codec informationfor re-encoding the video data Sb.

As described above, the storage capacity of the information buffer 255and the picture buffer 263 may correspond to the system delay (a timeperiod for several frames) of the editor and switcher 22. Thus, theinformation buffer 255 and the picture buffer 263 do not adverselyaffect the structure of the system.

The base band editor and switcher 22 outputs return base bandvideo/audio data Sc that has been edited to the splicer/transcoder. Thebase band data Sc is supplied to an MPEG re-encoder 253. The re-encoder253 receives codec information for an MPEG re-encoding processcorresponding to a video frame of the base band data Sc from aninformation buffer 255 through a path 254. Corresponding to the codecinformation for the re-encoding process, the data Sc is re-encoded for adesired bit quantity. The re-encoder 253 outputs a stream TS2 as theresult of an AB roll editing operation of the input streams A and B. Thecodec information for the re-encoding process contains for examplemoving vector, picture type, quantizing step size, and quantizing level.With the transcoding process, the deterioration of the picture qualitydue to a decoding-encoding chain can be suppressed.

Codec information is selected so that codec information is used insynchronization with the base band data Sc. When the read controller 257reads predetermined codec information, the read controller 257 suppliesto the re-encoder 253 an enable signal that represents the codecinformation can be used.

The input stream 268 and the base band signals Sa and Sb as the decodedresults are correlated in the relation of 1:1:1 on the time base. Whencodec information used in the decoding processes of the MPEG decoders252 a and 252 b is stored to the information buffer 255, the codecinformation is stored corresponding to an arrangement tag so that theyhave the relation of 1 to 1 on the time base. To store codec informationand manage the phases of the video data Sa and the video data Sbreceived from the splicer/transcoder 21 and the phase of the video dataSc returned from the base band editor and switcher 22, a managementtable 262 is disposed. The management table 262 controls the write/readoperations of the information buffer 255 and the picture buffer 263. Thewrite controllers 256 and 264 and the read controllers 257 and 265 areconnected to the management table 261.

The management table 261 controls the write/read operations of theinformation buffer 25 and the picture buffer 263 with the picture countvalue of the input stream and the frame count value of the return videodata Sc. A frame counter 258 counts the number of frames of the videodata Sc and sends a read request REQ with a read address correspondingto the count value to the management table 262. A picture counter 271detects a picture header from the input stream 268 and counts the numberof pictures. The number of pictures counted by the picture counter 271is supplied to a picture/frame index generator 272. The picture/frameindex generator 272 generates an index corresponding to a picture so asto arrange the management table 261 for pictures and information.

The management table 261 arranges the contents with the index andoutputs management information with an address as the count value of thenumber of frames of the video data Sc received from the frame counter258. The management table 261 has a structure of a ring buffer of whichinput information is successively written to an incremented address andthat a read pointer is incremented corresponding to the read requestREQ. Re-encode information of an address represented by the read pointeris read from the information buffer 255 and sent to the MPEG re-encoder253 through the path 254. The picture buffer 263 is controlled in thesame manner as the information buffer 255.

The re-encoder 253 is connected to a bit quantity estimator 259. The bitquantity estimator 259 performs a VBV buffer process. In other words,with the bit quantity estimator 259, the re-encoder 253 properlyperforms a re-encoding process so that the buffer of the decoder thatdecodes the MPEG bit stream TS2 does not overflow or underflow. When there-encoding process is performed, the target generated bit quantity issatisfied. In the normal encoding process, when the generated bitquantity of the re-encoder 253 is insufficient against the designatedtarget bit quantity, dummy data is added. In contrast, when thegenerated bit quantity exceeds the target bit quantity (in other words,in the situation that the buffer of the decoder will underflow), a macroblock skipping process or a process for causing the predictive residual(namely, the difference between a macro block MB of a predictive pictureand the relevant one of the considered picture) to be zero is performed.When such a process does not prevent the buffer from underflowing, thereproduced picture is affected by the processing method on the decoderside. Normally, until data is stored to the buffer, the reproducedpicture freezes.

Reference numeral 273 is a picture bit quantity counter that counts thegenerated bit quantity of the input stream 268. The picture bit quantitycounter 273 supplies the counted result to a VBV buffer simulator 274.The VBV buffer simulator 274 simulates a VBV buffer. The simulatedresult of the VBV buffer simulator 274 is supplied to the re-encodingstrategy planner 275. The re-encoding strategy planner 275 assigns andweights a generated bit quantity in the vicinity of an edit point so asto perform a re-encoding process. The assigned and weighted bit quantityat the relevant index slot of the management table 261 is written to arelevant index slot of the management table 261. The target bit quantity(information of assigned and weighted bit quantity) in the vicinity ofthe edit point is supplied to the bit quantity estimator 253 so that thegenerated bit quantity of the re-encoding of the re-encoder 253 becomesproper.

The splicer/transcoder shown in FIG. 8 detects an edit point withoutedit position information received from the editing device so as toobtain an edit state of the base band signal Sc. To do that, thesplicer/transcoder shown in FIG. 8 is equipped with a comparing portion270. The comparing portion 270 receives two original base band signalsSa and Sb and a return base band signal Sc. The two original base bandsignals Sa and Sb are received from the picture buffer 263. The baseband signal Sc is returned from the editor and switcher 22. In addition,the comparing portion 270 receives additional information such as GOPheader, picture header, macro block type, and moving vector from theinformation buffer 255. The comparing portion 270 detects an edit pointcorresponding to matches of the signals Sa and Sb that are output to theeditor and switcher 22 and the return signal Sc received therefrom. Inaddition, the comparing portion 270 determines whether or not codecinformation for a re-encoding process can be used for each picture andfor each macro block.

FIG. 9 shows an example of a base band signal Sc (referred to as picturePicC) as an edited result of a base band signal Sa (referred to aspicture PicA) and a base band signal Sb (referred to as picture PicB)according to the second embodiment of the present invention. Codecinformation is stored for each picture or each macro block of the baseband signal Sa and the base band signal Sb. In the example shown in FIG.9, a wipe process, a cross fade process, or the like is performed fortwo pictures at an edit point rather than switched from picture PicA topicture PicB. In other words, before the edit point, each frame of thepicture PicC matches each frame of the picture PicA. At the edit point,the frame of the picture PicC is an edited result of the frame of thepicture PicA and the frame of the picture PicB. After the edit point,each frame of the picture PicC matches each frame of the picture PicB.Codec information for each picture or each macro block of the base bandsignals Sa and Sb is stored.

The comparing portion 270 determines whether or not the picture PicAmatches the picture PicC in that state that their phases match. Inaddition, the comparing portion 270 determines whether or not thepicture PicB matches the picture PicC in that state that their phasesmatch. When the picture PicA does not match the picture PicC or when thepicture PicB does not match the picture PicC, the comparing portion 270detects a frame of an edit point. In reality, when the differencebetween pixels of a frame of one picture and pixels of a relevant frameof another picture is 0, the comparing portion 270 determines that thetwo pictures match. Otherwise, the comparing portion 270 determines thatthe two pictures do not match. For example, in the state that the phasesof two pictures match, each pixel of one picture and each pixel of theother picture are successively supplied to a subtracting circuit. Whenthe difference of two pixels is zero, the comparing portion 270determines that the two pictures do not match. Alternatively, when thenumber of pixels that do not match becomes a predetermined value, thecomparing portion 270 may determine that the two pictures do not match.

When such an edit point is detected, codec information used for there-encoding process of the re-encoder 253 is selected. When a picture isswitched for each frame, codec information to be re-used is selected foreach frame. However, when two pictures are placed in a picture at anedit point as with the example shown in FIG. 9, with a process forselecting codec information for each frame, the deterioration of thepicture quality against the re-encoding process cannot be sufficientlyprevented.

Thus, according to the second embodiment of the present invention, there-use of codec information (for a re-encoding process) is determinedfor each macro block. Next, an evaluating process and a determiningprocess for re-using codec information for each macro block will bedescribed. These processes are performed by the comparing portion 270.

As shown in FIG. 10, a macro block (denoted by MBA or MBB) of a picturePicA (or a picture PicB) and a macro block (denoted by MBC) of a picturePicC are compared in the state that the spatial position of the macroblock MBA (MBB) matches the spatial position of the macro block MBC. Inthis example, the size of each macro block is (16×16). The determinationfor match/non-match for each macro block is performed in the same manneras each frame.

FIG. 11 is a flow chart showing a process for determining whether or notcodec information can be re-used. When a video signal Sc (picture PicC)that has been edited is received from the editor and switcher, theprocess gets started. At step S1, original pictures A and B are readfrom the picture buffer 263.

At step S2 (as a comparing step), the pictures A and C are compared.When the determined result at step S2 is No (namely, the pictures A andC do not match), the flow advances to step S3. At step S3, the picturesB and C are compared. When the determined result at step S3 is No(namely, the pictures B and C do not match), the flow advances to stepS4. At step S4, macro blocks MBA and MBC are compared. When thedetermined result at step S4 is No (namely, the macro blocks MBA and MBCdo not match), the flow advances to step S5. At step S5, the macroblocks MBB and MBC are compared. As described above, two macro blocksare compared in the state that their spatial positions are the same.

When the determined result at step S2 is Yes (namely, PicA=PicC), withcodec information used for decoding the picture A, the picture C isre-encoded. In the MPEG system, there are three types of pictures thatare an I (Intra) picture as an intra-frame encoded picture, a P(Predictive) picture as an inter-frame forward predictive encodedpicture, and a B (Bidirectionally predictive) picture. Corresponding tothe picture type, the condition of the re-use of codec informationvaries. Thus, when the determined result at step S2 is Yes, the flowadvances to step S6 as a frame picture subroutine (that will bedescribed later).

Thereafter, the flow advances to step S7. At step S7, it is determinedwhether or not a predictive frame picture of the picture C is a framepicture of the picture A (namely, PIC (FW/BW), PIC Fg≠0?). When thedetermined result at step S7 is Yes (namely, the condition issatisfied), codec information of the relevant frame picture is preparedfor re-using codec information for each frame picture (at step S8). Whencodec information for each frame picture is re-used, codec informationfor a one-side frame picture may be used for re-encoding bidirectionalpredictive frame pictures.

When the determined result at step S7 is No (namely, the condition atstep S7 is not satisfied), as with the case that the condition ofPicA=PicC? at step S3 is not satisfied, the flow advances to step S3. Inother words, when a predictive frame picture of the picture C is not aframe picture of the picture A, the next condition is searched.

When the determined result at step S3 is Yes (namely, PicB=PicC), withcodec information of the picture B, the picture C is re-encoded. In thiscase, corresponding to the picture type, the condition of the re-use ofthe codec information varies. Thus, the flow advances to step S6 as theframe picture subroutine. Thereafter, the flow advances to step S9. Atstep S9, as with step S7 for the picture A, it is determined whether ornot a predictive frame picture of the picture C is a frame picture ofthe picture B. When the determined result at step S9 is Yes (namely, thecondition at step S9 is satisfied), the flow advances to step S8. Atstep S8, codec information of the relevant frame picture is prepared forre-using codec information for each frame picture. In reality, codecinformation of the relevant frame picture is read from the informationbuffer 255 and supplied to the re-encoder 253.

When the determined result at step S9 is No (namely, the condition atstep S9 is not satisfied), as with the case of the condition PicB≠PicC,the flow advances to step S4. In other words, when the conditions(PicA≠PicC) and (PicB≠PicC) are satisfied, it is determined whether ornot macro blocks of two pictures match (MBA=MBC). As shown in FIG. 9,when the pictures A and B co-exist in a frame picture at an edit pointof the picture C, the conditions (PicA≠PicC) and (PicB≠PicC) aresatisfied. In this case, codec information is re-used for each macroblock.

When the determined result at step S4 is Yes (namely, MBA=MBC), withcodec information of the macro block MBA, the macro block MBC isre-encoded. In the MPEG system, unlike with the picture types, there arefour macro block types that are an intra-frame encoded macro block, aforward inter-frame predictive macro block for predicting a future macroblock with a past macro block, a backward inter-frame predictive macroblock for predicting a past macro block with a future macro block, andan interpolative macro block for predicting a considered macro blockwith a past macro block and a future macro block.

An I picture contains only intra-frame encoded macro blocks. A P picturecontains intra-frame encoded macro blocks and forward inter-framepredictive macro blocks. A B picture contains all four types of macroblocks. Corresponding to the macro block type, the condition for there-use of codec information varies. Thus, when the determined result atstep S4 is No, the flow advances to step S10 as a macro block subroutine(that will be described later).

Thereafter, the flow advances to step S11. At step S11, it is determinedwhether or not a predictive macro block of the picture C is a macroblock of the picture A (namely, MB (FW/BW), MB Fg≠0 ?). When thedetermined result at step S11 is Yes, the flow advances to step S12. Atstep S12, codec information of the relevant macro block is prepared forre-using codec information for each macro block. When codec informationis re-used for each macro block, codec information of a one-side macroblock of bidirectional predictive macro blocks may be used.

When the determined result at step S11 is No (namely, the predictivemacro block of the picture C is not a macro block of the picture A), theflow advances to step S13. At step S13, codec information is notre-used. In this case, the transcoding process is not performed.Instead, an encoding process is simply performed.

When the determined result at step S4 is No (namely, MBA≠MBC), the flowadvances to step S5. At step S5, it is determined whether or not thecondition MBB=MBC is satisfied. When the determined result at step S5 isNo (namely, MBB≠MBC), the flow advances to step S13. At step S13, thecodec information is not re-used. When the determined result at step S5is Yes (namely, MBB=MBC), with the codec information of the macro blockMBB, the macro block MBC is re-encoded. In this case, corresponding tothe macro block type, the condition of the re-use of codec informationvaries. Thus, the flow advances to step S10 as the macro blocksubroutine. Thereafter, the flow advances to step S14. At step S14, aswith step S11, it is determined whether or not the predictive macroblock of the picture C is a macro block of the picture B. When thedetermined result at step S14 is Yes (namely, the condition at step S14is satisfied), the flow advances to step S12. At step S12, codecinformation of the relevant macro block is prepared for re-using codecinformation for each macro block. In reality, the codec information ofthe relevant macro block is read from the information buffer 255 andsupplied to the re-encoder 253. When the determined result at step S14is No (namely, the condition at step S14 is not satisfied), the flowadvances to step S13. At step S13, the codec information is not re-used.

Next, with reference to FIG. 12, the frame picture subroutine at step S6will be described in detail. At step S21, it is determined whether ornot the considered frame picture is an I picture. The picture type isdetermined corresponding to information of a picture header stored inthe information buffer 255. When the determined result at step S21 isYes (namely, the considered frame picture is an I picture), the flowadvances to step S22. At step S22, the picture flag PIC Fg is set to“1”. The picture flag PIC Fg that represents whether or not a predictiveframe picture is present for each picture is defined as follows.

PIC Fg=0: A relevant frame picture is absent.

PIC Fg=1: A relevant frame picture is present in the considered frame.

PIC Fg=2: A predictive frame picture that is a P picture is present inthe forward direction.

PIC Fg=3: A predictive frame picture that is a B picture is present inthe forward direction.

PIC Fg=4: A predictive frame picture that is a B picture is present inthe backward direction.

PIC Fg=5: Predictive frame pictures that are B pictures are present inthe forward and backward directions.

At step S22, when codec information is re-used, the picture flag PIC Fgthat represents a predictive frame picture is set. The picture flag isused to determine whether or not codec information is re-used. Inaddition, the picture flag is used to define codec information suppliedfrom the information buffer 255 to the re-encoder 253.

When the determined result at step S21 is No (namely, the consideredframe picture is not an I picture), the flow advances to step S23. Atstep S23, it is determined whether or not the considered frame pictureis a P picture. When the determined result at step S23 is Yes (namely,the considered frame picture is a P picture), the flow advances to stepS24. At step S24, a predictive frame picture is searched and detected.In this case, since the frame picture has been encoded so that it ispredicted with a past frame picture, a predictive frame picture based onthe encoding process is detected from the past frame picture. Theposition of the past predictive frame picture is determinedcorresponding to information of a GOP sequence contained in a GOPheader.

At step S25, it is determined whether or not the predictive framepicture of the picture C is present in the picture A (in the case of thesubroutine following step S2 shown in FIG. 11) or the picture B (in thecase of the subroutine following step S3 shown in FIG. 11). Thisdetermination is performed by comparing the predictive frame picturewith a frame picture of the picture A or B in the state that theirpositions are the same on the time base. When the determined result atstep S25 is Yes (namely, the predictive frame picture is present in thepicture A or B), the flow advances to step S22. At step S22, asdescribed above, the picture flag is set to “2”. When the determinedresult at step S25 is no (namely, the predictive frame picture is notpresent in the picture A or B), the picture flag PIC Fg is set to “0”(at step S26).

When the determined result at step S23 is No (namely, the consideredframe picture is not a P picture, but a B picture), the flow advances tostep S27. At step S27, the predictive frame picture is searched anddetected. Thereafter, the flow advances to step S28. At step S28, it isdetermined whether or not the predictive frame picture of the picture Cis present in the picture A or B. When the determined result at step S28is No (namely, the predictive frame picture of the picture C is notpresent in the picture A or B), the flow advances to step S26. At stepS26, the picture flag PIC Fg is set to “0”. When the determined resultat step S28 is Yes (namely, the predictive frame picture of the pictureC is present in the picture A or B), the flow advances to step S22. Atstep S22, as described above, depending on whether the predictive framepicture that is a B picture is present in the backward direction (past),in the forward direction (future), or in the forward/backwarddirections, the picture flag PIC Fg is set to “3”, “4”, or “5”,respectively.

In such a manner, the determination for the re-use of codec informationis performed for each frame picture. In the example shown in FIG. 9, theframe picture at the edit point is a B picture. In the case of a Bpicture, as shown with the flow chart in FIG. 12, a predictive framepicture (P picture) in the forward direction of the edit point and apredictive frame picture (P picture) in the backward direction of theedit point are searched. The predictive frame picture in the forwarddirection and the frame picture in the picture A are compared. When theymatch, it is determined that the predictive frame picture is present inthe forward direction. In addition, the frame picture in the backwarddirection and the frame picture in the picture A are compared. When theymatch, it is determined that the predictive frame picture is present inthe backward direction. Frame pictures in the forward direction and thebackward direction of an edit point may match a frame picture in thepicture A. In the example shown in FIG. 9, since two frame picturesco-exist in the considered frame picture, the conditions at steps S2 andS3 are not satisfied. Thus, a determining process for each macro blockis performed.

FIG. 13 is a flow chart showing a re-use determining process for codecinformation for each macro block (a macro block subroutine at step S10).At steps S31, S32, and S33, a macro block type is determined. The macroblock type is contained in a macro block mode of a macro block layer ofMPEG2 syntax. Corresponding to the information, the macro block type isdetermined.

At step S31, it is determined whether or not the considered macro blockis an intra-frame encoded macro block (I MB). When the determined resultat step S31 is No (namely, the considered macro block is not an I MB),the flow advances to step S32. At step S32, it is determined whether ornot the considered macro block is an interpolative (bidirectional) macrobock Bid MB. When the determined result at step S32 is No (namely, theconsidered macro block is not a Bid MB), the flow advances to step S33.At step S33, it is determined whether or not the considered macro blockis a backward inter-frame predictive macro block (or simply a backwardmacro block as shown in FIG. 13). When the determined result at step S33is No (namely, the considered macro block is neither an I MB, nor a BidMB, nor a backward macro block), the considered macro block is a forwardinter-frame predictive macro block (or simply a forward macro block asshown in FIG. 13).

It is determined whether or not codec information can be re-used foreach macro block type. When the determined result at step S31 is Yes(namely, the considered macro block is an I MB), the flow advances tostep S34. At step S34, a macro block flag MB Fg is set to “1”. When thedetermined result at step S31 is No (namely, the considered macro blockis other than an I MB), a moving vector is selected. It is determinedwhether or not a macro block corresponding to a predictive macro blockis present in the picture A or B at a position moved by the movingvector. When these conditions are satisfied, codec information can bere-used.

The macro block flag MB Fg that presents whether or not a predictivemacro block is present in the picture A or B for each macro block isdefined as follows.

MB Fg=0: A relevant macro block is absent.

MB Fg=1: A relevant macro block is present in the considered frame.

MB Fg=2: A relevant macro block is present in the forward direction ofthe edit point.

MB Fg=3: A relevant macro block is present in the backward direction ofthe edit point.

MB Fg=4: Relevant macro blocks are present in the forward direction andthe backward direction of the edit point.

MB Fg=5: A macro block is present in the forward side of the forwarddirection and the backward direction of the edit point.

MB Fg=6: A macro block is present in the backward side of the forwarddirection and the backward direction of the edit point.

The macro block flag is used to determine whether or not codecinformation can be refused for each macro block. In addition, the macroblock flag is used to define codec information supplied from theinformation buffer 255 to the re-encoder 253.

When the determined result at step S32 is Yes (namely, the consideredmacro block is a bidirectional macro block), a froward moving vector anda backward moving vector are prepared (at step S35). With these movingvectors, a predictive macro block is searched and detected (at stepS36). Since the position of the predictive macro block corresponds tothe GOP sequence, the predictive macro block is detected correspondingto information of the GOP sequence contained in the GOP header.

Thereafter, the flow advances to step S37. At step S37, it is determinedwhether or not the predictive macro block is present in the picture A(in the case of the subroutine following step S4 shown in FIG. 11) or inthe picture B (in the case of the subroutine following step S5 shown inFIG. 11). This determination is performed by comparing the predictivemacro block with a picture block equivalent to a macro block in thepicture A or B, the picture block being present at a position of whichthe predictive macro block is moved by the moving vector.

When the determined result at step S37 is Yes (namely, the predictivemacro block is present in the picture A and/or the picture B), the flowadvances to step S38. At step S38, the macro block flag MB Fg is set to“4”, “5”, or “6”. When the determined result at step S37 is No (namely,a macro block corresponding to the predictive macro block is notpresent), the flow advances to step S39. At step S39, the macro blockflag MB Fg is set to “0”. When the macro block flag MB Fg is “0”, itrepresents that codec information cannot be used for each macro block.

When frame pictures A and B co-exist as shown in FIG. 14, thedetermination is performed for each macro block. In the example shown inFIG. 14, frame pictures in the vicinity of an edit point arerepresented. In the example shown in FIG. 14, the picture type of theconsidered frame picture is a B picture. In addition, two macro blocksin the forward direction and the backward direction of the edit pointare represented. In the frame picture at the edit point, macro blocks MBin the frame picture A are compared with picture blocks equivalent tomacro blocks in a past frame picture A at a position moved by a forwardmoving vector. (In FIG. 14, these macro blocks are denoted by GOOD). Inaddition, these macro blocks are compared with picture blockscorresponding to macro blocks in a future frame picture B at a positionmoved by a backward moving vector. In this case, both the blocks do notmatch the picture blocks (denoted by NG). Thus, in this case, the macroblock flag MB Fg is set to “5”.

Macro blocks MB in the frame picture B at the edit point are comparedwith picture blocks equivalent to macro blocks in the frame pictures Aand B at positions moved by a forward moving vector and a backwardmoving vector. As shown in FIG. 14, a macro block matches a macro blockin a future frame picture (in this example, a P picture) moved by abackward moving vector. Thus, in this case, the macro block flag MB Fgis set to “6”. When the frame pictures A and B do not co-exist, pictureblocks equivalent to macro blocks corresponding to a predictive macroblock are present in the forward direction and the backward direction ofthe edit point. Thus, the macro block MB Fg is set to “4”.

In FIG. 13, when the determined result at step S33 is Yes (namely, theconsidered macro block of the frame picture C is a backward macroblock), the flow advances to step S41. At step S41, a backward movingvector is prepared. A picture block equivalent to a macro block in afuture frame picture A or B at a position moved by a moving vector issearched and detected (at step S42). Thereafter, the flow advances tostep S43. At step S43, the detected picture block is compared with thepredictive macro block of the considered macro block and determinedwhether or not a picture block equivalent to a macro block correspondingto the predictive macro block is present.

When the determined result at step S43 is Yes (namely, a picture blockequivalent to a macro block corresponding to the predictive macro blockis present), the flow advances to step S44. At step S44, the macro flagMB Fg is set to “3”. When the determined result at step S43 is No(namely, a picture block equivalent to a macro block corresponding tothe predictive macro block is absent), the flow advances to step S39. Atstep S39, the macro block flag MB Fg is set to “0”.

When the determined result at step S33 is No (namely, the consideredmacro block in the frame picture C is not a backward macro block, but aforward macro block), the flow advances to step S45. At step S45, aforward moving vector is prepared. Thereafter, the flow advances to stepS46. At step S46, a picture block equivalent to a macro block in thepast frame picture A or B at a position moved by a moving vector issearched and detected. Thereafter, the flow advances to step S47. Atstep S47, the detected macro block is compared with the predictive macroblock of the considered macro block and determined whether or not apicture block equivalent to a macro block corresponding to thepredictive macro block is present.

When the determined result at step S47 is Yes (namely, a picture blockequivalent to a macro block corresponding to a predictive macro block ispresent), the flow advances to step S48. At step S48, the macro blockflag MB Fg is set to “2”. When the determined result at step S47 is No(namely, a picture block equivalent to the relevant macro block is notpresent), the flow advances to step S39. At step S39, the macro blockflag MB Fg is set to “0”.

In such a manner, the validity of the re-use of codec information foreach macro block is determined. Thus, as shown in FIG. 9, even if twooriginal frame pictures co-exist in a frame picture at an edit point,with codec information for each macro block, the frame picture C can bere-encoded. Thus, codec information can be more finely re-used than thecase of the re-encoding process for each frame picture. Consequently,the deterioration of the picture quality can be suppressed.

In the above description, although the MPEG system is used as acompression encoding system, another compression encoding system can beused.

In the editing controlling apparatus according to the present invention,input/output interfaces with the archiver/server and so forth areperformed using encoded streams. An interface with an editing device isperformed with a base band signal. In addition, with a transcodingprocess, the deterioration of the picture quality due to adecoding-encoding chain can be remarkably suppressed. Since it is notnecessary to add re-encoded information for the transcoding process to abase band signal and to send the resultant signal to an external editingdevice or a storage device, an editing operation can be performedwithout affecting the external device. Thus, a material such as apicture material can be stored as a stream. In addition, it is notnecessary to change the structure of the editing device in abroadcasting station or a studio. From a stand point of the user, theediting system composed of the editing device and the editingcontrolling device edits data as a stream. However, the editing systemactually edits data as a base band signal.

In addition, a base band signal and a bit stream are correlated. Thus, atranscoding process is performed for only required pictures and switchedwith relevant bit streams. Consequently, the distortion due to thetranscoding process can be remarkably suppressed. Moreover, while acompressed material is directly stored and edited, a base band materialis directly stored and edited.

In addition, according to the present invention, since the editingsystem directly handles an MPEG stream, a multi-channel system can beaccomplished for a network circuit disposed in a broadcasting station.Thus, the material transmission resources of the broadcasting stationcan be effectively used. In consideration of the relation between acenter station and local stations for a ground wave broadcast and therelation between a cable operator and head end stations for a CATVsystem, according to the present invention, a CM of a center station canbe substituted with a CM of a local station. In addition, a logo of abroadcasting station can be inserted almost free of deterioration of theresultant bit stream.

In addition, according to the present invention, as described as thesecond embodiment, when a base band signal decoded from an encoded bitstream is edited and then re-encoded to a stream, it is not necessary toreceive edit position information from an editing device. Thus, atransmission line for transmitting the edit position information can beomitted. In addition, a process for interpreting edit information as atime code into a stream on the time base can be omitted.

In addition, according to the present invention as described as thesecond embodiment, when codec information is re-used for the transcodingprocess, codec information can be also selected in a smaller data unitthan a picture (namely, for each macro block as well as each picture).Thus, even if two or more original materials co-exist in a frame pictureat an edit point, the deterioration of the picture quality against there-encoding process can be suppressed.

1. An editing apparatus, comprising: first decoding means for decoding afirst encoded bit stream to generate a first base band signal; seconddecoding means for decoding a second encoded bit stream to generate asecond base band signal; detecting means for matching phases of thefirst base band signal, the second base band signal, and a third baseband signal, and comparing these signals to detect an edit position atwhich the first base band signal and the second base band signal areconnected, the third base band signal being obtained by editing thefirst base band signal and the second base band signal; re-encodingmeans for re-encoding the third base band signal to generate a thirdencoded bit stream; and controlling means for controlling saidre-encoding means to re-use first codec information used to generate thefirst base band signal and second codec information used to generate thesecond base band signal corresponding to the edit position detected bysaid detecting means to re-encode the third base band signal, whereinthe first and second codec information includes a moving vector, apicture type, a quantizing step size, and a quantizing scale.
 2. Theediting apparatus as set forth in claim 1, wherein said controllingmeans controls said re-encoding means to re-encode the third base bandsignal only in a predetermined period including the edit positiondetected by said detecting means.
 3. The editing apparatus as set forthin claim 1, further comprising: selecting means for selecting the thirdencoded bit stream generated by said re-encoding means in thepredetermined period including the edit position and selecting one ofthe first encoded bit stream and the second encoded bit stream in otherthan the predetermined period.
 4. The editing apparatus as set forth inclaim 1, wherein said detecting means matches the phases of the signalsof each picture and compares the signals to detect the edit position ofeach picture.
 5. The editing apparatus as set forth in claim 4, whereinsaid controlling means controls said re-encoding means to selectivelyre-use the first codec information and the second codec information ofeach picture corresponding to the edit position of each picture tore-encode the third base band signal.
 6. The editing apparatus as setforth in claim 4, wherein said detecting means obtains the difference ofpixels in the same spatial position of pictures of the first base bandsignal and the third base band signal to detect the edit position ofeach picture.
 7. The editing apparatus as set forth in claim 4, whereinsaid detecting means obtains the difference of pixels in the samespatial position of pictures of the second base band signal and thethird base band signal to detect the edit position of each picture. 8.The editing apparatus as set forth in claim 6, wherein said detectingmeans detects a picture of which the difference of the pixels is notzero as the edit position.
 9. The editing apparatus as set forth inclaim 7, wherein said detecting means detects a picture of which thedifference of the pixels is not zero as the edit position.
 10. Theediting apparatus as set forth in claim 8, wherein said detecting meansdetects a picture having a predetermined number of pixels whosedifference is not zero as the edit position.
 11. The editing apparatusas set forth in claim 9, wherein said detecting means detects a picturehaving a predetermined number of pixels whose difference is not zero asthe edit position.
 12. The editing apparatus as set forth in claim 4,wherein when a picture of the first base band signal and a picture ofthe second base band signal are present at the edit position of eachpicture, said controlling means controls said re-encoding means to matchthe phases of the signals of each macro block, compares the signals, andselectively re-uses the first codec information and the second codecinformation of each macro block to re-encode the third base band signal.13. The editing apparatus as set forth in claim 4, further comprising:determining means for determining the picture type of a picture at theedit position detected by said detecting means, wherein said controllingmeans detects a prediction objective picture at the edit positioncorresponding to the picture type determined by said determining meansto determine whether to re-use the first codec information and thesecond codec information of each picture.
 14. The editing apparatus asset forth in claim 13, wherein when the prediction objective picture isnot present in the third base band signal, said control means does notre-use the first codec information and the second codec information. 15.The editing apparatus as set forth in claim 13, further comprising:setting means for setting a picture flag that identifies the presence ofa prediction objective picture at the edit position corresponding to thepicture type determined by said determining means, wherein saidcontrolling means references the picture flag that is set by saidsetting means to determine whether to re-use the first codec informationand the second codec information of each picture.
 16. The editingapparatus as set forth in claim 12, further comprising: determiningmeans for determining the macro block type of a macro block at the editposition detected by said detecting means, wherein said controllingmeans detects a prediction objective macro block at the edit positioncorresponding to the macro block type determined by said determiningmeans to determine whether to re-use the first codec information and thesecond codec information of each macro block.
 17. The editing apparatusas set forth in claim 16, further comprising: setting means for settinga macro block flag that identifies the presence of a predictionobjective macro block at the edit position corresponding to the macroblock type determined by said determining means, wherein saidcontrolling means references the macro block flag that is set by saidsetting means to determine whether to re-use the first codec informationand the second codec information of each macro block.
 18. An editingapparatus, comprising: first decoding means for decoding a first encodedbit stream to generate a first base band signal; second decoding meansfor decoding a second encoded bit stream to generate a second base bandsignal; detecting means for matching the phases of the first base bandsignal and a third base band signal and comparing these signals todetect an edit position at which the first base band signal and thesecond base band signal are connected, the third base band signal beingobtained by editing the first base band signal and the second base bandsignal; re-encoding means for re-encoding the third base band signal togenerate a third encoded bit stream; and controlling means forcontrolling said re-encoding means to selectively re-use first codecinformation used to generate the first base band signal and second codecinformation used to generate the second base band signal correspondingto the edit position detected by said detecting means to re-encode thethird base band signal, wherein the first and the second codecinformation includes a moving vector, a picture type, a quantizing stepsize, and a quantizing scale.
 19. An editing apparatus, comprising:first decoding means for decoding a first encoded bit stream to generatea first base band signal; second decoding means for decoding a secondencoded bit stream to generate a second base band signal; detectingmeans for matching the phases of the second base band signal and a thirdbase band signal and comparing these signals to detect an edit positionat which the first base band signal and the second base band signal areconnected, the third base band signal being obtained by editing thefirst base band signal and the second base band signal; re-encodingmeans for re-encoding the third base band signal to generate a thirdencoded bit stream; and controlling means for controlling saidre-encoding means to selectively re-use first codec information used togenerate the first base band signal and second codec information used togenerate the second base band signal corresponding to the edit positiondetected by said detecting means to re-encode the third base bandsignal, wherein the first and the second codec information includes amoving vector, a picture type, a quantizing step size, and a quantizingscale.
 20. A re-encoding apparatus, comprising: detecting means formatching the phases of a first base band signal, a second base bandsignal, and a third base band signal and comparing these signals todetect an edit position at which the first base band signal and thesecond base band signal are connected, the first base band signal beingobtained by decoding a first encoded bit stream, the second base bandsignal being obtained by decoding a second encoded bit stream, the thirdbase band signal being obtained by editing the first base band signaland the second base band signal; re-encoding means for re-encoding thethird base band signal to generate a third encoded bit stream; andcontrolling means for controlling said re-encoding means to selectivelyre-use first codec information used to generate the first base bandsignal and second codec information used to generate the second baseband signal corresponding to the edit position detected by saiddetecting means to re-encode the third base band signal, wherein thefirst and the second codec information includes a moving vector, apicture type, a quantizing step size, and a quantizing scale.
 21. Are-encoding apparatus, comprising: detecting means for matching thephases of a first base band signal and a third base band signal andcomparing these signals to detect an edit position at which the firstbase band signal and the second base band signal are connected, thefirst base band signal being obtained by decoding a first encoded bitstream, the third base band signal being obtained by editing the firstbase band signal and a second base band signal, the second base bandsignal being obtained by decoding a second encoded bit stream;re-encoding means for re-encoding the third base band signal to generatea third encoded bit stream; and controlling means for controlling saidre-encoding means to selectively re-use first codec information used togenerate the first base band signal and second codec information used togenerate the second base band signal corresponding to the edit positiondetected by said detecting means to re-encode the third base bandsignal, wherein the first and the second codec information includes amoving vector, a picture type, a quantizing step size, and a quantizingscale.
 22. A re-encoding apparatus, comprising: detecting means formatching the phases of a second base band signal and a third base bandsignal and comparing these signals to detect an edit position at which afirst base band signal and the second base band signal are connected,the second base band signal being obtained by decoding a second encodedbit stream, the third base band signal being obtained by editing thefirst base band signal and the second base band signal, the first baseband signal being obtained by decoding a first encoded bit stream;re-encoding means for re-encoding the third base band signal to generatea third encoded bit stream; and controlling means for controlling saidre-encoding means to selectively re-use first codec information used togenerate the first base band signal and second codec information used togenerate the second base band signal corresponding to the edit positiondetected by said detecting means to re-encode the third base bandsignal, wherein the first and the second codec information includes amoving vector, a picture type, a quantizing step size, and a quantizingscale.
 23. A re-encoding apparatus, comprising: re-encoding means forre-encoding a third base band signal to generate a third encoded bitstream, the third base band signal being obtained by editing a firstbase band signal and a second band signal, the first base band signalbeing obtained by decoding a first encoded bit stream, the second baseband signal being obtained by decoding a second encoded bit stream; andcontrolling means for controlling said re-encoding means to selectivelyre-use first codec information used to generate the first base bandsignal and second codec information used to generate the second baseband signal corresponding to an edit position at which the first baseband signal and the second base band signal are connected and that isdetected by matching the phases of the first base band signal, thesecond base band signal, and the third base band signal and comparingthese signals to re-encode the third base band signal, wherein the firstand the second codec information includes a moving vector, a picturetype, a quantizing step size, and a quantizing scale.
 24. A re-encodingapparatus, comprising: re-encoding means for re-encoding a third baseband signal to generate a third encoded bit stream, the third base bandsignal being obtained by editing a first base band signal and a secondband signal, the first base band signal being obtained by decoding afirst encoded bit stream, the second base band signal being obtained bydecoding a second encoded bit stream; and controlling means forcontrolling said re-encoding means to selectively re-use first codecinformation used to generate the first base band signal and second codecinformation used to generate the second base band signal correspondingto an edit position at which the first base band signal and the secondbase band signal are connected and that is detected by matching thephases of the first base band signal and the third base band signal andcomparing these signals to re-encode the third base band signal, whereinthe codec information includes a moving vector, a picture type, aquantizing step size, and a quantizing scale.
 25. A re-encodingapparatus, comprising: re-encoding means for re-encoding a third baseband signal to generate a third encoded bit stream, the third base bandsignal being obtained by editing a first base band signal and a secondband signal, the first base band signal being obtained by decoding afirst encoded bit stream, the second base band signal being obtained bydecoding a second encoded bit stream; and controlling means forcontrolling said re-encoding means to selectively re-use first codecinformation used to generate the first base band signal and second codecinformation used to generate the second base band signal correspondingto an edit position at which the first base band signal and the secondbase band signal are connected and that is detected by matching thephases of the second base band signal and the third base band signal andcomparing these signals to re-encode the third base band signal, whereinthe codec information includes a moving vector, a picture type, aquantizing step size, and a quantizing scale.
 26. An editing method,comprising the steps of: decoding a first encoded bit stream to generatea first base band signal; decoding a second encoded bit stream togenerate a second base band signal; matching the phases of the firstbase band signal, the second base band signal, and a third base bandsignal, and comparing these signals to detect an edit position at whichthe first base band signal and the second base band signal areconnected, the third base band signal being obtained by editing thefirst base band signal and the second base band signal; re-encoding thethird base band signal to generate a third encoded bit stream; andcontrolling the re-encoding step to selectively re-use first codecinformation used to generate the first base band signal and second codecinformation used to generate the second base band signal correspondingto the edit position detected at the detecting step to re-encode thethird base band signal, wherein the first and the second codecinformation includes a moving vector, a picture type, a quantizing stepsize, and a quantizing scale.
 27. An editing method, comprising thesteps of: decoding a first encoded bit stream to generate a first baseband signal; decoding a second encoded bit stream to generate a secondbase band signal; matching the phases of the first base band signal anda third base band signal and comparing these signals to detect an editposition at which the first base band signal and a second base bandsignal are connected, the third base band signal being obtained byediting the first base band signal and the second base band signal;re-encoding the third base band signal to generate a third encoded bitstream; and controlling the re-encoding step to selectively re-use firstcodec information used to generate the first base band signal and secondcodec information used to generate the second base band signalcorresponding to the edit position detected at the detecting step tore-encode the third base band signal, wherein the first and the secondcodec information includes a moving vector, a picture type, a quantizingstep size, and a quantizing scale.
 28. An editing method, comprising thesteps of: decoding a first encoded bit stream to generate a first baseband signal; decoding a second encoded bit stream to generate a secondbase band signal; matching the phases of the second base band signal anda third base band signal and comparing these signals to detect an editposition at which the first base band signal and a second base bandsignal are connected, the third base band signal being obtained byediting the first base band signal and the second base band signal;re-encoding the third base band signal to generate a third encoded bitstream; and controlling the re-encoding step to selectively re-use firstcodec information used to generate the first base band signal and secondcodec information used to generate the second base band signalcorresponding to the edit position detected at the detecting step tore-encode the third base band signal, wherein the first and the secondcodec information includes a moving vector, a picture type, a quantizingstep size, and a quantizing scale.
 29. A re-encoding method, comprisingthe steps of: matching the phases of a first base band signal and athird base band signal and comparing these signals to detect an editposition at which the first base band signal and the second base bandsignal are connected, the first base band signal being obtained bydecoding a first encoded bit stream, the third base band signal beingobtained by editing the first base band signal and a second base bandsignal, the second base band signal being obtained by decoding a secondencoded bit stream; re-encoding the third base band signal to generate athird encoded bit stream; and controlling the re-encoding step toselectively re-use first codec information used to generate the firstbase band signal and second codec information used to generate thesecond base band signal corresponding to the edit position detected atthe detecting step to re-encode the third base band signal, wherein thefirst and the second codec information includes a moving vector, apicture type, a quantizing step size, and a quantizing scale.
 30. Are-encoding method, comprising the steps of: matching the phases of asecond base band signal and a third base band signal and comparing thesesignals to detect an edit position at which a first base band signal andthe second base band signal are connected, the second base band signalbeing obtained by decoding a second encoded bit stream, the third baseband signal being obtained by editing the first base band signal and thesecond base band signal, the first base band signal being obtained bydecoding a first encoded bit stream; re-encoding the third base bandsignal to generate a third encoded bit stream; and controlling there-encoding step to selectively re-use first codec information used togenerate the first base band signal and second codec information used togenerate the second base band signal corresponding to the edit positiondetected at the detecting step to re-encode the third base band signal,wherein the first and the second codec information includes a movingvector, a picture type, a quantizing step size, and a quantizing scale.31. A re-encoding method, comprising the steps of: matching the phasesof a first base band signal, a second base band signal, and a third baseband signal and comparing these signals to detect an edit position atwhich the first base band signal and the second base band signal areconnected, the first base band signal being obtained by decoding a firstencoded bit stream, the second base band signal being obtained bydecoding the second encoded bit stream, the third base band signal beingobtained by editing the first base band signal and the second base bandsignal; re-encoding the third base band signal to generate a thirdencoded bit stream; and controlling the re-encoding step to selectivelyre-use first codec information used to generate the first base bandsignal and second codec information used to generate the second baseband signal corresponding to the edit position detected at the detectingstep to re-encode the third base band signal, wherein the first and thesecond codec information includes a moving vector, a picture type, aquantizing step size, and a quantizing scale.
 32. A re-encoding method,comprising the steps of: re-encoding a third base band signal togenerate a third encoded bit stream, the third base band signal beingobtained by editing a first base band signal and a second band signal,the first base band signal being obtained by decoding a first encodedbit stream, the second base band signal being obtained by decoding asecond encoded bit stream; and controlling the re-encoding step toselectively re-use first codec information used to generate the firstbase band signal and second codec information used to generate thesecond base band signal corresponding to an edit position at which thefirst base band signal and the second base band signal are connected andthat is detected by matching the phases of the first base band signaland the third base band signal and comparing these signals to re-encodethe third base band signal, wherein the first and the second codecinformation includes a moving vector, a picture type, a quantizing stepsize, and a quantizing scale.
 33. A re-encoding method, comprising thesteps of: re-encoding a third base band signal to generate a thirdencoded bit stream, the third base band signal being obtained by editinga first base band signal and a second base band signal, the first baseband signal being obtained by decoding a first encoded bit stream, thesecond base band signal being obtained by decoding a second encoded bitstream; and controlling the re-encoding step to selectively re-use firstcodec information used to generate the first base band signal and secondcodec information used to generate the second base band signalcorresponding to an edit position at which the first base band signaland the second base band signal are connected and that is detected bymatching the phases of the second base band signal and the third baseband signal and comparing these signals to re-encode the third base bandsignal, wherein the first and the second codec information includes amoving vector, a picture type, a quantizing step size, and a quantizingscale.
 34. A re-encoding method, comprising the steps of: re-encoding athird base band signal to generate a third encoded bit stream, the thirdbase band signal being obtained by editing a first base band signal anda second band signal, the first base band signal being obtained bydecoding a first encoded bit stream, the second base band signal beingobtained by decoding a second encoded bit stream; and controlling there-encoding step to selectively re-use first codec information used togenerate the first base band signal and second codec information used togenerate the second base band signal corresponding to an edit positionat which the first base band signal and the second base band signal areconnected and that is detected by matching the phases of the first baseband signal, the second base band signal, and the third base band signaland comparing these signals to re-encode the third base band signal,wherein the first and the second codec information includes a movingvector, a picture type, a quantizing step size, and a quantizing scale.